Über submarine Denudation und chemische Sedimente     

Arnold Heim 《International Journal of Earth Sciences》1924,15(1):1-47

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Matthew Fontaine Maury und die Brüsseler Konferenz 1853     

Arnold Schumacher 《Ocean Dynamics》1953,6(2):87-93

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Element concentrations and variations along a 120-km transect in southern Norway – Anthropogenic vs. geogenic vs. biogenic element sources and cycles     

Clemens Reimann  Arnold Arnoldussen  Peter Englmaier  Peter Filzmoser  Tor Erik Finne  Robert G. Garrett  Friedrich Koller  Øystein Nordgulen 《Applied Geochemistry》2007

Rock samples and the C-, B- and O-horizons of soils developed on these rocks were collected in forested areas along a 120-km south–north transect in southern Norway, passing through the city of Oslo. Forty samples (1 site/3 km) were analysed for 37 chemical elements (Ag, Al, As, Au, B, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ga, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Sc, Se, Sr, Te, Th, Ti, Tl, U, V, W and Zn) following an aqua regia digestion; pH (water extract) and loss on ignition were also determined. The O-horizon soils were additionally analysed for Pt. Gold is the only element that shows a clear anthropogenic peak in the O-horizon soils collected from the city of Oslo. Silver, Au, Bi, Cd, Hg, Pb, S, Sb, Se and Sr all show a strong enrichment in the O-horizon when compared to the underlying C-horizon or the bedrock along the full length of the transect. Neither geology nor anthropogenic input of elements dominate the observed patterns. The most important factors for the observed element concentrations in the O-horizon are weathering, uptake (or rejection) of elements by plants and the kinetics of decay of the organic material in the O-horizon. Climate, especially temperature and precipitation, has an important influence on the formation and decay rates of the organic soil layer. Acid precipitation will delay the decomposition of the organic layer and lead to a natural enrichment of several metals in the O-horizon. Land use change, deforestation and liming can all increase the decay kinetics of organic matter and thus result in a release of the stored element pool.  相似文献   

A Bayesian approach to estimating tectonic stress from seismological data   总被引：2，自引：0，他引：2  

Richard Arnold  John Townend 《Geophysical Journal International》2007,170(3):1336-1356

Earthquakes are conspicuous manifestations of tectonic stress, but the non-linear relationships between the stresses acting on a fault plane, its frictional slip, and the ensuing seismic radiation are such that a single earthquake by itself provides little information about the ambient state of stress. Moreover, observational uncertainties and inherent ambiguities in the nodal planes of earthquake focal mechanisms preclude straightforward inferences about stress being drawn on the basis of individual focal mechanism observations. However, by assuming that each earthquake in a small volume of the crust represents a single, uniform state of stress, the combined constraints imposed on that stress by a suite of focal mechanism observations can be estimated. Here, we outline a probabilistic (Bayesian) technique for estimating tectonic stress directions from primary seismological observations. The Bayesian formulation combines a geologically motivated prior model of the state of stress with an observation model that implements the physical relationship between the stresses acting on a fault and the resultant seismological observation. We show our Bayesian formulation to be equivalent to a well-known analytical solution for a single, errorless focal mechanism observation. The new approach has the distinct advantage, however, of including (1) multiple earthquakes, (2) fault plane ambiguities, (3) observational errors and (4) any prior knowledge of the stress field. Our approach, while computationally demanding in some cases, is intended to yield reliable tectonic stress estimates that can be confidently compared with other tectonic parameters, such as seismic anisotropy and geodetic strain rate observations, and used to investigate spatial and temporal variations in stress associated with major faults and coseismic stress perturbations.  相似文献   

Deutung diskordanter Zirkonalter der Silvrettadecke und des Gotthardmassivs (Schweizer Alpen)     

B. Grauert  A. Arnold 《Contributions to Mineralogy and Petrology》1968,20(1):34-56

U-Pb isotopic analyses are reported for zircons of nine igneous rocks and high grade metamorphic paragneisses from the Silvretta nappe and the Gotthard massif, Switzerland.Following Silver and Deutsch (1961) the zircon populations isolated from six of these rocks were devided into series of size fractions with varying uranium content. An extensive Rb-Sr investigation has been made on some of these rock samples and their minerals (Arnold and Jäger, 1965: Gotthard massif, Grauert, 1966: Silvretta nappe). Rb-Sr measurements on biotites and mineral isochrons of individual gneiss samples yield ages which indicate the end of the Alpine and the Hercynian (=Variscan) metamorphism. Other measurements give mixed ages between these events. The U-Pb investigation of zircons, however, yield criteria for an even older event, 400 to 500 m.y. ago.The isotopic relationship indicates a strong episodic disturbance of the U-Pb systems in the paragneiss zircons with high losses of radiogenic lead. In a Concordia diagram the best fit lines to the data points of the paragneiss zircons from the Gotthard massif as well as from the Silvretta nappe trend both toward the data points of the orthogneiss zircons and intersect the Concordia at approximately 440 m.y. Rb-Sr analyses of the granitic orthogneisses from the Silvretta nappe (Flüela granite gneisses) gave a well defined isochron of 428 m.y. (=1.47×10^–11y^–1). This value agrees rather well with the age given by the intersection of the best fit lines to the paragneiss zircons with the Concordia.Considering the geological and petrographical observations we interpret this disturbance of the U-Pb systems in the paragneiss zircons as the result of an influence of regional high grade metamorphism and anatectic melting together with the formation of igneous rocks during the Caledonian petrogenesis.In the Silvretta the uranium rich zircons from the Flüela granite gneisses reflect a disturbance and lead loss probably during the Hercynian metamorphism. In the Gotthardmassif the zircons from a quartz diorite and an ultrabasic inclusion in this diorite, however, show no or only a slight influence of the later Hercynian and Alpine metamorphisms. The apparent ages of the zircons in the ultrabasic inclusion are nearly concordant (Pb²⁰⁶/U²³⁸: 448 m.y., Pb²⁰⁷/ U²³⁵: 452 m.y., Pb²⁰⁷/Pb²⁰⁶: 472 m.y.). There is in all orthogneiss zircons some evidence of older inhereted U-Pb components besides new zircon growth.If we assume an episodic model for the lead loss and a disturbance 450 m.y. ago the minimum primary age of the detrital zircon components in the paragneisses would be 1500 m.y.

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Der eine von uns (B.G.) möchte den Herren Prof. Dr. M. Grünenfelder und Prof. Dr. P. Signer vom Labor für Geochronologie des Instituts für Kristallographie und Petrographie der Eidgenössischen Technischen Hochschule Zürich seinen Dank für ihr Interesse und die großzügige Unterstützung bei der Durchführung dieser Arbeit aussprechen. Herr Prof. Dr. M. Grünenfelder und Herr Dr. R. Pidgeon haben ihn in die Arbeitsweise der U-Pb-Isotopenanalyse eingeführt. Herr Dr. V. Köppel sowie alle oben genannten Herren haben durch ihre wertvollen Ratschläge und kritischen Diskussionen diese Arbeit wesentlich gefördert. Ihnen und auch allen anderen Angehörigen des Labors für Geochronologie, die zum Gelingen der Arbeit beigetragen haben, sei herzlichst gedankt.

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Herr Dr. L. Rybach hat in dankenswerter Weise von vier Zirkonfraktionen die Urankonzentration durch Gamma-Spektrometrie bestimmt.

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Wir beide möchten Frau Prof. Dr. E. Jäger und Herrn Prof. Dr. E. Niggli vom Mineralogisch-Petrographischen Institut der Universität Bern für ihr wohlwollendes Interesse und die kritische Durchsicht des Manuskriptes danken.  相似文献   

Carbon on surfaces of magnesium oxide and olivine single crystals. Diffusion from the bulk or surface contamination?     

I. S. T. Tsong  U. Knipping  C. M. Loxton  C. W. Magee  G. W. Arnold 《Physics and Chemistry of Minerals》1985,12(5):261-270

We have conducted detailed studies of the behavior of carbon on the surfaces of MgO and olivine single crystals using various surface analytical techniques: viz. secondary ion mass spectrometry (SIMS), Auger electron spectrometry (AES) and X-ray photoelectron spectrometry (XPS). In order to distinguish without ambiguity the effect of diffusion of carbon from the bulk to the surface and the effect of surface contamination by carbon-containing species, the experiments were conducted in ultrahigh vacuum, i.e. 10^?11–10^?9 torr. In addition to MgO and olivine single crystals, we have conducted the same studies on TiO₂, MnO, SiO₂ and Ta₂O₅ which serve as blank samples. The MgO and olivine samples were also intentionally implanted with known doses of carbon and the mobility of this particular carbon was investigated in detail. Our results show that the bulk carbon content in MgO is around 40 wt. ppm, considerably lower than the quantities quoted by Freund and co-workers in the past. We also show that the carbon in both MgO and olivine does not display any rapid diffusion behaviour leading to surface segreation in the temperature range 78–723 K, in contrast to the previous findings of Freund and co-workers.  相似文献   

Tracing quartz through the environment     

D Lal  J R Arnold 《Journal of Earth System Science》1985,94(1):1-5

Quartz, SiO₂, a pure mineral with tight crystal structure, is widespread in rocks and soil. Cosmic rays produce¹⁰Be (t _1/2=1·5×10⁶, yr) and²⁶Al (t _1/2=7·05×10⁵ yr) in quartz exposed at or near the earth’s surface. The use of accelerator mass spectrometry permits measurement of these nuclides in samples exposed at sea level for typical periods.In situ production makes interpretation relatively straightforward. Potential applications include age determination, measurement of erosion and deposition rates, and use as a tracer for continental weathering processes.  相似文献   

Rare earth distributions in clay minerals and in the clay-sized fraction of the Lower Permian Havensville and Eskridge shales of Kansas and Oklahoma   总被引：1，自引：0，他引：1  

Robert L Cullers  Sambhudas Chaudhuri  Bill Arnold  Moon Lee  Carlton W Wolf 《Geochimica et cosmochimica acta》1975,39(12):1691-1703

The REE (rare earth element) content of a wide variety of clay mineral groups have been analyzed using radiochemical neutron activation and have been found to be quite variable in absolute REE content (range of ∑REE = 5.4–1732) and less variable in relative REE content (range of chondritenormalized La/Lu = 0.9–16.5). The variable REE content of the clay mineral groups is probably determined by the REE content of the source rock from which the clay mineral was derived and not from the separate minerals in the rock.The clay-sized fractions of the Havensville and Eskridge shales of Kansas and Oklahoma have similar relative REE distributions and identical negative Eu anomaly size as the composite of NAS (N. American shales), but an absolute REE content (range of ∑REE = 46–348) that may differ significantly from the composite of NAS. The clay-sized fraction of samples from any given outcrop did not vary much in absolute or relative REE content, but samples from northern Oklahoma, probably composed of continental to near-shore marine sediments, have higher absolute REE contents and higher La/Lu ratios than samples of marine deposits in Kansas (e.g. mean ∑REE in Oklahoma = 248; mean ∑REE in Kansas = 69–116). The differencess in the REE content between samples in Oklahoma and Kansas may be caused by chemical weathering processes in the source area, exchange reactions in the environment of deposition, or diagenesis and do not appear to be a result of the different clay minerals.Most samples have Eu anomalies relative to chondrites (range of Eu/Sm ratios of samples = 0.035–1.17; chondrites = 0.35). Some montmorillonites and kaolinites are anomalous in Eu relative to the NAS (range of Eu/Sm ratios of samples = 0.056–0.21; NAS = 0.22). These anomalies may be inherited from source rocks with Eu anomalies originally produced by igneous processes, or they may be produced by chemical weathering processes in the source area.  相似文献   

Die Nutzung des Wassers aus den Tagebauen nördlich Leipzigs     

K.-H. Arnold 《洁净——土壤、空气、水》1980,8(5):429-433

Außerordentlich große Wassermengen werden bei der Entwässerung der Tagebaue gehoben, aber bisher nur zu einem geringen Teil unmittelbar für die Wasserversorgung genutzt. Die planmäßige und abgestimmte Nutzung der Naturressourcen verlangt die Prüfung der Möglichkeiten zur Nutzbarmachung zumindest eines Teiles dieser Wässer für die Trinkwasserversorgung besonders in Ballungsgebieten. Auf Grund der besonderen geologischen Gegebenheiten im Raum nördlich Leipzigs bestehen günstige Voraussetzungen. Maßnahmen zum Schutze und der Nutzung dieser Wässer sind eingeleitet. Bauaufwand und technische Ausrüstungen für die Wasserversorgung sind den Besonderheiten der Tagebauwasserbereitstellung anzupassen.  相似文献   

Professor Albert Defant siebzig Jahre     

Arnold Schumacher  Günther Böhnecke 《Ocean Dynamics》1954,7(1-2):1-1

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